Lowering device



May 6, 1947. o. w. LUNDBLAD LowERING DEVICE Filed Jan. 24, 1946 IIIIIIIIIIIIIIIIIIIII OSCAR W. LUNDBLAD INVENTOR. mgm.;

AGENT Patented May 6, 1947 LOWERING DEVICE Oscar W. Lundblad, Ishpeming, Mich., assignor to Hercules Powder Company, Wilmington, Del., a corporation of Delaware Application January 24, 1946, Serial No. 643,187

Claims.

This invention relates to a lowering device and more particularly to a device for lowering explosive cartridges in drill holes.

In blasting practice, it is customary to drill a plurality of vertical holes varying from a few feet to possibly 100 feet or more in depth. Explosive cartridges are then lowered into these holes and exploded in a well known manner.

There are several ways of loading the vertical holes. When working with explosives of relatively low sensitivity, it may be possible to drop the explosive down the borehole, the paper shell, or wrappngs surrounding the explosive often being ruptured when the cartridge strikes the bottom of the hole or the top of the cartridge previously inserted. While this method may work with explosives of low sensitivity, and in relatively dry holes in which the borehole is suciently smooth and straight, it is not satisfactory with explosives of higher sensitivity and in holes partially filled with water or holes having rough, uneven sides.

In other cases the cartridges are encased in a harness, bag, web of netting or similar material. Cartridges provided with a loop of cord or fibrous material as a means of suspension also find widespread use. Lowering means are attached to the top of the encasing member or cartridge loop and the cartridge lowered into the hole at a desired speed and under the control of the operator. If the sides of the holes are rough and uneven, there is a tendency for the bag or harness to be caught by the rough and uneven sides, thus blocking the hole and rendering it necessary to dislodge the cartridge. All of this requires additional time and effort and in some cases is quite dangerous. The lowering means heretofore used have been very cumbersome to handle, recovery being an uncertain and timeconsuming operation.

It is an object of this invention to provide an eflicient, recoverable lowering device for explosive cartridges.

It is a further object of this invention to provide a lowering device having a positive release.

A further object of this invention is to provide a lowering device that will permit withdrawal of the cartridge from an obstructed hole without disengagement with said cartridge. Other objects of this invention will appear hereinafter, the novel features and combinations being set forth in the appended claims.

Generally described, the present invention comprises a hook, a cutter slidably retained therein and attached to a hanger rod in preloaded attachment to the hook, and means of adjustment of the amount of preloading. A tensile force applied to the hanger rod vwith suicient momentum to overcome the preloaded and statically loaded forces on the hook will cause relative movement of the shaft and hook and thereby actuate the cutter to sever material suspended from said hook.

An embodiment of the invention has been chosen for purposes of illustration and description and is shown in the accompanying drawings forming a part of the specification and wherein like reference symbols refer to like parts whereever they occur.

Fig. l is an elevational view of the invention.

Fig. 2 is an end view of Fig. l.

Fig 3 is an enlarged fragmentary cross-sectional view taken along line 3-3 of Fig. 2.

With reference to the drawings, the lowering device of the present invention has a hook I0 defining a U-shaped retaining chamber II from which may be suspended a cord or like fibrous material, not shown, in turn supporting a cartridge or cartridge encasing means containing cartridges likewise not shown. A guard strip I2 rigidly attached at one end to the tip I3 of the hook I and bearing in spring-loaded abutment to a shank i4 of the hook Ill at the other end, closes the open end of the U-shaped retaining chamber II. Manually forcing the guard strip I2 away from spring-loaded abutment with the shank I4 will permit passage to or from the retaining chamber I I of a cord or like librous ma.- terial used in suspending explosive cartridges or encasing means.

A11 eye I5 in a hanger rod I is adapted to form a means whereby the lowering cable or rope, not shown, can be attached to the invention. The hanger rod I5 is held in preloaded attachment to the shank I4 of the hook Ill by means of a coiled compression spring I'I centrally encircling said rod and retained in a cylindrical chamber I8 of the shank I 4 by a knurled adjustment screw I9. Manual adjustment of the position of the adjustment screw in threaded relationship to the shank Ill determines the amount of preloading or force exerted by the spring I1 against the collar 29 held in rigid attachment te the hanger rod I6 by a dowel pin 2l.

A cutter 2-2 is pivotally supported between a pin 23 and a disk 2d which is an integral part of the hanger rod I6. Upward movement of the hanger rod I6 will raise the cutter 22 to a position in the retaining chamber II as shown in Fig. 3, thus cutting the cord or fibrous material,

not shown. Calibrations 25 on the shank I4 of the hook I indicate the desirable position of the adjustment screw |9 for the various loadings on the hook I0.

In actual practice, a cylindrical explosive cartridge provided with a loop of cord attached to one end as a suspending means was used in loading a plurality of vertically drilled holes. The cord was inserted in .the retaining chamber by forcing the guard strip from abutment with the shank of the hook. The adjustment screw was adjusted to a position to cause a preloaded force to be exerted against the collar of the hanger rod slightly exceeding the opposing force caused by the weight of the suspended cartridge. Lowering of the cartridges by a strong rope tied to the eye of the hanger rod was accomplished without difficulty. When a cartridge reached the bottom of the hole, the lowering rope was given a sudden jerk. Sufficient reactive force was thereby imparted to the hanger rod to overcome the spring loading and cause momentary travel upward of the rod in the shank of the hook, carrying the cutter up into the retaining chamber to sever the cord.

The present invention greatly simpliies the operation of lowering explosive cartridges and has reduced the initial investment in and i'nain-V tenance of the equipment required. Time spent in the handling of cartridges and recovery of the loading equipment has also been markedly reduced.

What I claim and desire to protect by Letters -Patent is:

1. In a device for lowering explosive cartridges the combination of a hook; a cutter slidably retained in said hook; a hanger rod in slidable preloaded attachment to said hook and adapted to actuate the cutter to sever material retained by the hook upon application of sucient reactive forcerto the rod to cause relative movement between the hook and said rod; and adjustment means whereby the amount of preloading can be regulated.

2.. In a device for lowering explosive cartridges the combination of a hook; a cutter slidably retained in said hook; a hanger rod in slidable preloaded attachment to said hook and adapted to actuate the cutter to sever material retained by the hook upon application of sufficient reactive force to the rod to cause relative movement between the hooi: and said rod; adjustment means whereby the amount of preloading can be regulated; and guard means whereby accidental dislodgment of the material retained by the hook is prevented.

3. In a device for lowering explosive cartridges the combination of a hook; a cutter slidably retained in said hook; a hanger rod in slidable preloaded attachment to said hook and adapted to actuate the cutter to sever material retained by the hook upon application of suiiicient reactive force to the rod to cause relative movement between the hook and said rod; adjustment means whereby the amount of preloading can be regulated; guard means whereby accidental dislodgment of the material retained by the hook is prevented; and calibrations on said hook whereby the amount of preloading is visually indicated.

4. In a device for lowering explosive cartridges the combination of a hook; a cutter slidably retained in said hook and in pivotal attachment to said hook; a hanger rod in slidable preloaded attachment to said hook and adapted to actuate the cutter to sever material held by said hook; and adjustment means whereby the amount of preloading can be regulated.

5. In a device for lowering explosive cartridges the combination of a hook; a cutter slidably retained in said hook and. in pivotal attachment to said hook; a hanger rod in slidable preloaded attachment to said hook and adapted to actuate the cutter to sever material held by said hook; adjustment means whereby the amount of preloading can be regulated; and calibrations on said hook whereby the amount of preloading is visually indicated.

OSCAR W. LUNDBLAD. 

